Over the years many developments have been made in the endoscope art. Particularly, these developments have been attempts to provide endoscopes which will serve a variety of functions and which are maintained in a sterile condition during use.
Ersek et al. U.S. Pat. Nos. 3,794,091 and 3,809,072 each disclose a flexible sheath which is sterile at the time of manufacture and can be rolled up onto an endoscope to provide sterility. However, there is no seal at the proximate end of the sheath and therefore bacteria can enter between the endoscope and sheath and there is no provision for maintaining the distal end of the endoscope in a sterile or protected condition.
Russel U.S. Pat. No. 3,866,601 discloses a speculum in which a penetrating tube slidably receives a guide tube and is surrounded by a flexible sheath.
Ibe U.S. Pat. No. 4,132,227 discloses an endoscope surrounded by a hollow cylindrical sheath extending toward but not to the distal end of the endoscope in order to create a fluid channel in the space between the sheath and the endoscope.
Smith U.S. Pat. No. 4,201,199 discloses an endoscope surrounded by a rigid glass or plastic tube having an enlarged bulb at its distal end to space tissue away from the viewing window of the endoscope. The window is formed at an angle to provide viewing of a site offset from the axis of the endoscope.
Yoon U.S. Pat. No. 4,254,762 discloses an endoscope surrounded by a sheath having a transparent lens at its distal end. The sheath may be at least partially open at its distal end for use with endoscopes having biopsy channels.
Hampson U.S. Pat. No. 4,327,735 discloses a catheter surrounded by a transparent, collapsible sleeve through which the catheter projects at its distal end.
Silverstein et al. U.S. Pat. No. 4,646,722 discloses another endoscope having a sterile flexible sheath which can be rolled up along the endoscope. A channel is provided between the endoscope and sheath through which biopsies can be taken. The sheath is not sealed at the upper end and will not maintain the sterility which is required within an operating room.
D'Amelio U.S. Pat. No. 4,721,097 discloses another flexible sheath for use on an endoscope which has no seal at the upper end and does not provide the sterility required in an operating room.
Sidall et al. U.S. Pat. No. 4,741,326 discloses a further flexible sheath which is rolled up along the endoscope and does not provide sterility or protection of the entire endoscopic device.
Brown British Patent No. 1,405,025 discloses a proctoscope surrounded by a concentric tube for providing a fluid channel.